Thecus N16000 Series User Manual page 88

After Standby server has communicated with Active Server successfully,
then the state will changed:
Click "Yes" to reboot both Active and Standby server.
If the communication is failed then you will have error message as below.
WARNING
NOTE
Conditions in which the standby server will take over for the active server:
1. Active server RAID is damaged
2. Loss of the active server's data port connection
3. Active server goes down for any other reason
When the active server encounters the above-mentioned situations, the standby
server (PMS) will immediately take over for the active server. The standby server's
system log will show "HA changed to active, getting resources", and "Healthy: The
RAID [HA] on system [PMS] is healthy now."
Please be sure that "Standby" unit volume
size must be larger then "Active" unit. Or the
HA synchronize will result failed.
LAN3 is used for heart beat in HA function to
connect "Active" and "Standby" systems peer to
peer.
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